Disposable vitrectomy handpiece

ABSTRACT

Electric vitrectomy handpieces are provided. The handpiece includes a motor, a clutch mechanism, an oscillating drive mechanism, a cutting tip and a handle. The motor is attached to the clutch, and the clutch is attached to the oscillating drive mechanism. When the motor is operational, the clutch expands to engage the oscillating drive mechanism and the oscillating drive mechanism converts the rotational motion of the clutch to the reciprocating motion of the cutting tip. When the motor is at rest, the clutch retracts to allow aspiration.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority to and the benefit of U.S. ProvisionalPatent Application Ser. No. 60/876,796, filed on Dec. 21, 2006, entitledDISPOSABLE VITRECTOMY HANDPIECE, the entire content of which isincorporated herein by reference.

FIELD OF THE INVENTION

The invention is directed to electric vitrectomy handpieces, and moreparticularly, the invention is directed to disposable electricvitrectomy handpieces that are small in size and light in weight.

BACKGROUND OF THE INVENTION

Vitreous is a normally clear, gel-like substance that fills the centerof the eye. Certain problems affecting the eye may require a vitrectomy,or surgical removal of all or a part of the vitreous. To perform avitrectomy, various instruments are used including a vitrectomyhandpiece, a light pipe and an infusion line or port. The vitrectomyhandpiece includes a cutter for removing all or a portion of the eye'svitreous. The light pipe is used as a light source, and the infusionline or port is used to replace fluid and maintain proper pressure inthe eye.

Current vitrectomy handpieces have several parts, many of which can berather expensive. For example, current vitrectomy handpieces includepositional sensors that detect the position of the motor to determinewhen to begin aspiration. This increases the cost of manufacture,thereby increasing the cost of the device to the ultimate consumer.Moreover, while these devices are designed to be reused, the cutting tipmust be replaced. Replacement cutting tips can be expensive, with acommon model costing over $100.

In addition to expense, current vitrectomy handpieces include severalelectrical and pneumatic lines attached to the device, making the devicecumbersome to operate and maneuver. Also, in order to accommodate thenumber of parts included in the device and the electric and pneumaticlines, the handpieces tend to be larger, contributing to the cumbersomenature of the device. Accordingly, a need exists for a less cumbersome,less expensive device that is easy to maneuver and comfortable to handleduring surgery.

SUMMARY OF THE INVENTION

The invention is directed to vitrectomy handpieces that are light inweight and small in size. The light weight and small size of the devicemakes it easy to maneuver and comfortable to handle during surgery. Inone embodiment, a vitrectomy handpiece includes an electric motor, aclutch mechanism, an oscillating drive mechanism and a cutting tip. Themotor is attached to the clutch which is attached to the oscillatingdrive mechanism. The motor may be any electric motor suitable for use invitrectomy handpieces. The oscillating drive mechanism may be anymechanism capable of converting rotational motion of the motor toreciprocating motion of the cutting tip.

The clutch mechanism engages the oscillating drive mechanism when themotor is running and is stationary when the motor is at rest. When themotor is at rest, the clutch mechanism allows aspiration, and when themotor is running, the clutch mechanism engages the oscillating drivemechanism, which converts the rotational motion of the clutch toreciprocating motion of the cutting tip.

In one embodiment, the vitrectomy handpiece is disposable. Thedisposable vitrectomy handpiece according to this embodiment ismanufactured using low cost parts for assembly and manufacture. Forexample, an inexpensive, disposable motor may be used to manufacture adisposable vitrectomy handpiece according to an embodiment of thepresent invention.

The inventive vitrectomy handpieces are small in size and light inweight, enabling greater maneuverability of the device by the surgeon.In addition, the inventive vitrectomy handpieces are ergonomicallydesigned, making the handpiece comfortable to handle during surgery.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the attached drawings in which:

FIG. 1 is a photograph comparing a vitrectomy handpiece according to anembodiment of the present invention with a vitrectomy handpieceaccording to the prior art;

FIG. 2A is a partial cross-sectional view of a vitrectomy handpieceaccording to one embodiment of the present invention;

FIG. 2B is an exploded view of area B in FIG. 2A;

FIG. 2C is an exploded view of area C in FIG. 2A;

FIG. 3 is a partially cut-away side view of a vitrectomy handpieceaccording to one embodiment of the present invention;

FIG. 4 is an exploded schematic view of a motor, clutch mechanism, drivemechanism and cutting tip of a vitrectomy handpiece according to oneembodiment of the present invention;

FIGS. 5A through 5E are schematic diagrams depicting the motion of aclutch mechanism and drive mechanism during a cutting process of avitrectomy handpiece according to one embodiment of the presentinvention; and

FIG. 6 is an exploded view of a vitrectomy handpiece according to oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are directed to disposable electricvitrectomy handpieces. The handpieces are useful with, for example,20-gauge or smaller instrumentation (e.g. 23, 25-gauge). The handpiecesare small in size and cost-efficient. According to one embodiment of theinvention, the small size is achieved by a disposable tool including acutter tip integrated into the tool handle. In another embodiment, costefficiency is achieved by a tool using plastic components and aninexpensive, disposable motor. Although described as disposable and madeof plastic, it is understood that the device need not be disposable andmay be made of any suitable material other than plastic, for example,metal. The drive mechanism and vitreous cutting tip have performancecharacteristics that are equivalent to or better than existinghandpieces. Moreover, the vitrectomy handpiece maintains a substantiallyconstant aspiration duty cycle over a range of operating speeds, suchas, for example, about 3,000 to about 10,000 cpm or about 600 to about6000 cpm.

According to one embodiment of the invention, the vitrectomy handpieceis well balanced, light in weight and has low rotational and linetorque. Accordingly, the handpiece is easily maneuverable by thesurgeon. In one embodiment, the vitrectomy handpiece is smaller thanconventional electric handpieces, thereby facilitating mobility.According to one embodiment of the present invention, the pneumaticlines are incorporated into the handle or fully enclosed within thehandle, reducing clutter and improving ease of manipulation by thesurgeon. The electrical lines are much lighter than those inconventional cutters, reducing the amount of external torsionexperienced by the surgeon. According to one embodiment, the electricallines may be disposable lines that are integral with the handpiece. Inanother embodiment, a reusable line connecting a machine (external orotherwise) to the handpiece may be used. In yet another embodiment, aninternal power supply may be used instead of electrical lines.

The vitrectomy handpiece according to embodiments of the presentinvention is an inexpensive surgical tool providing an electricalternative to pneumatic cutters. In some embodiments, the vitrectomyhandpiece is inexpensive and disposable, eliminating the need forreplacement parts. The vitrectomy handpiece may be provided as a sterilepackage with the cutting tip incorporated directly into the handpiece.As the handpiece may be provided fully assembled, the time needed toprepare for surgery may be significantly reduced. Also, with disposabledesigns, the surgeon may bill directly for the tools used in theprocedure, which option is not available when using a reusablevitrectomy tool with replacement parts.

Many considerations are taken into account when designing a vitrectomyhandpiece. Some such considerations include cost, size, low noise andvibration, aspiration duty cycle and traction. In the disposableembodiments of the present invention, cost is a concern. To reduce cost,the components of the vitrectomy handpiece may be manufactured in highvolume, using low cost techniques such as injection molding, CNCmachining, overmolding, deep drawing, EDM, and the like. Additionally,reducing part count and handpiece size significantly reduces the totalcost of the handpiece. To that end, integrating the tip into thehandpiece not only lowers part count, but also reduces the overall sizeof the unit, yielding a size comparable to or smaller than existingvitrectomy handpieces (e.g. the Alcon Innovit). As shown in FIG. 1, avitrectomy handpiece 100 according to one embodiment of the presentinvention is smaller than the Alcon Innovit handpiece 102.

Another consideration in designing vitrectomy handpieces is minimizingnoise and vibration. High levels of noise and vibration adversely affectmaneuverability of the tool during surgery, and makes it difficult forthe surgeon to make precise cuts. To minimize noise and vibration, thedrive mechanism according to one embodiment has balanced components,smooth transitions as the cutter is extended and retracted, and goodalignment of the drive components. These characteristics increase theprecision of the internal components and therefore impact the method ofmanufacture. In one embodiment of the invention, to reduce noise andvibration, the vitrectomy handpiece has an invariable cutting duty cycleat a wide range of operating speeds. In addition, to reduce traction incomparison to existing electric cutters, a vitrectomy handpieceaccording to one embodiment of the present invention has a maximum cutspeed targeted between about 6000 cpm and about 10,000 cpm. Another wayto dampen vibration includes providing a rubber, foam, silicon, or otherlike tube around the motor.

FIGS. 2 through 4 are detailed diagrams of various vitrectomy cutters 20according to certain embodiments of the present invention. According tothe illustrated embodiment, the cutter 20 includes a motor 1, a clutchmechanism 2, an oscillating drive mechanism 7, and a cutter tip 10mounted inside a handle 14. The handle 14 is used to mount and align thevarious components, provide ergonomic design for the surgeon, and routeaspiration lines. In one embodiment, the cutter tip 10 is directlyintegrated into the handle 14. This integration helps reduce complexityand part count by eliminating the interface components between the tipand the handle.

According to one embodiment, the motor 1 is attached to the clutch 2.The clutch expands to engage the oscillating drive 7 and cutter tip 10when the motor 1 is operational and retracts to allow aspiration via theaspiration line 15 when the motor 1 is at rest. The oscillating drive 7converts the motor 1 rotation into a smooth reciprocating motion of thecutter tip 10. The oscillating drive may be any device capable ofconverting rotary to oscillating linear motion, such as, for example, acrankshaft.

Although the clutch is described as allowing aspiration when the motoris off, it is understood that the vitrectomy handpiece aspirates duringthe cutting process as well. During a cutting process, the aspirationport 201 opens and closes repeatedly as the cutter is extended andretracted. Aspiration occurs through the open aspiration port 201throughout the cutting process. However, in conventional vitrectomyhandpieces, when the motor is turned off, the cutter may either beextended to close the aspiration port or retracted to open theaspiration port, and the position of the cutter is random depending onwhen during the cutting process the motor is turned off. In contrast,according to one embodiment of the present invention, the clutchmechanism 2 5 retracts the cutter when the motor is turned off, ensuringthat the aspiration port is open when the motor is turned off.

The actuation of the clutch 2 may be achieved in different ways. Forexample, the clutch 2 may retract by reversing the motor 1. In thisembodiment, the motor automatically runs in reverse for a short periodwhen the motor turns off. The reverse motion of the motor causes theclutch to retract, thereby allowing aspiration via the aspiration line15.

In an alternative embodiment, a spring return may be employed so thatwhen the motor 1 is off, the clutch 2 retracts. This alternative clutchmechanism may be used in conjunction with a spring to retract the clutchand open the aspiration port when the cutter is turned off. The designof the previous embodiment uses slow reversed motion of the motor toopen the aspiration port. A design with light springs allows the clutchto retract without any reverse motion of the motor. This helps simplifythe control required for the tool, but may increase the complexity andthus the overall cost of the unit.

The clutch mechanism 2 is used to engage the cutter tip 10 when thehandpiece is operated, and allow aspiration when the cutter isstationary. Existing electric vitrectomy handpieces use a positionalsensor to monitor the position of the motor to determine when toinitiate aspiration. In such conventional handpieces, the motor isrotated to a position where the aspiration port is open when the cutteris at rest. This allows full aspiration through the tip of theinstrument when it is not being used to cut. However, the vitrectomyhandpieces according to embodiments of the present invention useclutching mechanisms to reduce cost and part count, as well as toimprove maneuverability of the instrument. The clutch eliminates theneed for a positional sensor, which not only reduces overall unit cost,but also reduces the number of electrical lines attached to the cutter.The smaller cord attached to the cutter makes it easier to maneuver bythe surgeon. This also results in less line torque.

According to one embodiment, the clutch mechanism 2 includes twocomponents that rotate relative to each other when torque is transmittedacross them. With reference to FIGS. 2B and 4, a groove 200 is cut inthe first component 3. The groove may have any suitable profile, and inone embodiment, is half of a sinusoidal groove. The second component 5captivates a ball 4 which rides in the groove 200. When the motor isturned on, torque is transmitted across the two components of the clutchmechanism, causing them to rotate relative to one another. As the twocomponents rotate with respect to one another, the ball rolls or slidesalong the groove, causing the two components to expand or contract. Whenthe ball reaches the end of the groove, it comes to a hard stop.Subsequently, both components of the clutch rotate together,transmitting rotary motion to the oscillating drive mechanism 7. Theoscillating drive mechanism 7 converts the rotational motion into smoothreciprocating linear motion of the cutter.

As an alternative to the groove 200, the clutch may include a pin ridingon a cam (not shown), or the like. Regardless of the embodiment,however, the clutch/cam may be implemented as a single component toreduce cost, or be separated into two elements.

FIGS. 5A to 5E illustrate portions of the oscillating drive mechanism 7and clutch mechanism 2 during a cutting process. The cutter tip 10 ateach step is shown in a box 104 a-104 e below the drive and clutchmechanisms. The motor provides rotary motion which is depicted by curvedarrows 106 a-106 e. At the position illustrated in FIG. 5A, the cutteris starting from rest and beginning to cut. In this position, both theclutch 2 and cutter tip 10 are retracted and the aspiration port 201 isopen. As the motor begins to rotate, the clutch expands until it reachesthe engaged position (the position illustrated in FIG. 5B). The clutchremains engaged as long as the cutter is cutting (the positionsillustrated in FIGS. 5B through 5E). When the clutch is engaged, theoscillating drive mechanism 7 travels enough to move the cutter acrossthe aspiration port 201. At the positions illustrated in FIGS. 5Cthrough 5E, the clutch 2 is engaged, and the oscillating drive 7 isopening and closing the cutter. At the position illustrated in FIG. 5C,the oscillating drive mechanism 7 closes the cutter for the first cut.The cutter is then open at the position illustrated in FIG. 5D andclosed again at the position illustrated in FIG. 5E.

The motor may be any suitable motor known in the art, and in oneembodiment, may be a disposable motor. Using disposable motors, whichare generally less expensive than their reusable counterparts, reducesnot only the cost of the motor but also the cost of the vitrectomyhandpiece. A disposable design also allows use of plastic components andgearing. When purchased in high volumes, high quality, miniature DCmotors with gearing may cost about $30 or more. Although such disposablemotors typically have shorter lifespans than their non-disposablecounterparts, because the motor is disposable, the lifespan requirementis reduced compared to non-disposable motors. For a disposableinstrument, the longevity of the motor is not as stringent, and morecost effective motors can be considered.

Small DC motors generally require gearing due to the output speed range(which may be about 600 cpm to about 6000 cpm), and the high torqueneeded (stall torque of about 7 mNm). Typical small DC motors run atspeeds above about 5000 rpm, with many of them having free runningspeeds above about 15000 rpm. Pre-geared motors meet the shaft speed andtorque requirements, but they increase both price and footprint.

Gearing small DC motors is another option to optimize overall cost. Onemethod of achieving this includes using a motor with relatively hightorque (stall torque of about 2 to about 3 mNm) and relatively low freerunning speed (about 10,000 rpm), and incorporating minimal gearing toobtain the desired speed. Gearing may include a frictional drive, asingle set of spur gears, a plastic planetary gear, or a harmonic drive.Typically, a motor with high torque and low free running speed will belarger than the faster running lower torque models. The cost of thedifferent motors will be similar. To reduce the footprint of thevitrectomy handpiece, a smaller motor may be used with gearing similarto a harmonic drive. This type of gearing has a relatively low partcount and allows for high reduction ratios in a small space. Ultimately,the gearing decision will be a cost trade-off analysis of the variousdesigns and projected cost of manufacture.

According to one embodiment, the handle 14 of the vitrectomy handpiecenot only holds the motor 1 and drive mechanisms 2 and 7, but also theaspiration line 15. Routing the aspiration line through the handlereduces clutter and improves maneuverability of the tool. According toone embodiment, the aspiration line begins inside the handle and isrouted to a port in the back of the handle. A small electrical line isbundled with the aspiration line at the back of the handle in a singlecord. The cord (including the aspiration line and electrical line) maybe integrated with the handpiece to form a single component.

According to other embodiments of the invention, the vitrectomyhandpiece interfaces with existing cutter tips 10 a as is illustrated inFIG. 6. As shown in FIG. 6, a vitrectomy handpiece according to oneembodiment of the present invention including a motor 1 a, clutchmechanism 2 a and oscillating drive mechanism 7 a interfaces with acommercially available cutter tip 10 a.

According to another embodiment of the invention, as shown in FIGS. 2-3,the vitrectomy handpiece incorporates the cutter tip 10 into the handle14 and the aspiration line 15 is routed through the handle 14. Thisconfiguration eliminates the need for an externally connected aspirationline, and thus improves maneuverability of the handpiece. In oneembodiment, the aspiration line 15 may be routed around the motor, asshown in FIGS. 2A and 3. In addition to yielding all the benefits ofrouting the aspiration line inside the handle, this configuration coolsthe motor, keeping it from overheating, as the aspiration fluid runsacross the motor 1 through the aspiration line 15. Such a configurationalso helps dampen vibration.

In another embodiment of the invention, a speed sensor may beincorporated into the handpiece for sensing speed, proper operation ofthe handpiece, and the like. The speed sensor may include a sensor and amagnet. In another embodiment, instead of using a sensor, speed may bemeasured by measuring a current ripple as the motor rotates, measuringcurrent/voltage curves and extrapolating speed based on the measureddata, and the like.

According to another embodiment of the invention, stall of the handpiecemay be detected by looking at the current draw to find failure.

In one embodiment, tabs may be integrated into the handle to preventrotation of the tip by the drive mechanism.

According to another embodiment, a seal is provided. As shown in FIGS. 2and 3, the seal may include a seal housing 11, an o-ring or diaphragmseal 12 and a seal retainer 13.

To be viable alternatives to pneumatic cutters, the cost of theinventive vitrectomy handpieces should be comparable to or less thanexisting cutter tips. To reduce cost, according to one embodiment, allcomponents in the design are made of plastic. However, it is understoodthat the present invention is not limited to plastic, and that any othermaterial that lends itself to high volume and low cost manufacturingtechniques may be employed in lieu of or in addition to plastic.

The components of the vitrectomy handpiece may be manufactured bymolding or CNC techniques conventional in the art. Molding may have ahigher upfront tooling cost, but provides low unit cost unit whenpurchased in large volumes. CNC parts provide improved componenttolerances, but unit cost is increased when purchased in large volumes.If high tolerance is required for the clutch mechanism, molding may beused in conjunction with a CNC finishing pass (bored hole or asinusoidal cam cut). A study on performance versus part tolerance may beevaluated to understand the exact specifications for the mold and/or CNCparts.

Optimal gearing of the handpiece may be achieved by testing traction andcutting efficiency as a function of cutter rate. This testing will allowoptimization of top speed. With this information, the gearing of thehandpiece may be modified for operation at an optimal cut rate.

Although this invention has been described with respect to certainspecific embodiments, those skilled in the art will have no difficultydevising variations to the described embodiments which in no way departfrom the scope and spirit of the present invention. For example,although the present invention has been described with respect toelectric vitrectomy handpieces, those of ordinary skill in the art willappreciate that the described designs may also apply to pneumaticvitrectomy handpieces. Furthermore, to those skilled in the variousarts, the invention itself herein will suggest solutions to other tasksand adaptations for other applications. It is Applicants' intention tocover all such uses of the invention and those changes and modificationswhich could be made to the embodiments of the invention herein chosenfor the purpose of disclosure without departing from the spirit andscope of the invention. Thus, the present embodiments of the inventionshould be considered in all respects as illustrative and notrestrictive.

1. A vitreous cutter comprising: a motor configured to provide rotarymotion; a handle; a cutter tip; an aspiration line; and a clutchmechanism coupled to the motor and the cutter tip, the clutch mechanismconfigured to expand for engaging the cutter tip when the motor isactivated, and retract for aspiration through the aspiration line whenthe motor is at rest.
 2. The vitreous cutter according to claim 1,wherein the clutch mechanism comprises a component including a groove.3. The vitreous cutter according to claim 2, wherein the groove is asinusoidal groove.
 4. The vitreous cutter according to claim 1, whereinthe motor is a disposable motor.
 5. The vitreous cutter according toclaim 1, wherein the cutter tip is integrated into the handle.
 6. Thevitreous cutter according to claim 1, wherein the aspiration line isrouted through the handle.
 7. The vitreous cutter according to claim 6,wherein the aspiration line is routed around the motor.
 8. The vitreouscutter according to claim 1, further comprising a means for sensing aspeed of the cutter tip.
 9. The vitreous cutter according to claim 8,wherein the means for sensing the speed of the cutter tip comprises asensor and a magnet.
 10. The vitreous cutter according to claim 1,further comprising a means for detecting motor failure by monitoringhigh current draw.
 11. The vitreous cutter according to claim 1, furthercomprising an oscillating drive mechanism configured to convert therotary motion of the motor to oscillatory linear motion.
 12. Thevitreous cutter according to claim 1, further comprising a means forreducing vibration in the handle.
 13. The vitreous cutter according toclaim 12, wherein the means for reducing vibration in the handlecomprises a rubber or foam tube surrounding the motor, wherein the tubeis compressed against the motor by the handle.
 14. The vitreous cutteraccording to claim 12, wherein the means for reducing vibration in thehandle comprises a compressed silicone tubing surrounding the motor. 15.The vitreous cutter according to claim 1, further comprising a means forpreventing heat transfer from the motor to the handle.
 16. The vitreouscutter according to claim 15, wherein the means for preventing heattransfer from the motor to the handle comprises an insulating materialsurrounding the motor.
 17. A vitreous cutter comprising: a motorconfigured to provide rotary motion; a handle; a cutter tip; anaspiration line; and a clutch mechanism coupled to the motor and thecutter tip, the clutch mechanism configured to expand for engaging thecutter tip when the motor is activated, and retract for aspirationthrough the aspiration line when the motor is at rest, the clutchmechanism comprising first and second components rotatable relative toeach other.
 18. The vitreous cutter according to claim 17, wherein theclutch further comprises a ball riding in a groove in the firstcomponent, the second component maintaining the ball in the groove ofthe first component.